Use assert(Not)Regex instead of assertTrue or assertFalse in tests

[Flamefire]

This PR is now split into smaller PRs (<= 5 modules, <= ~100 lines):

• [1/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5240
• [2/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5241
• [3/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5242
• [4/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5243
• [5/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5244
• [6/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5245
• [7/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5246
• [8/8] Use assert(Not)Regex instead of assertTrue or assertFalse in tests #5247

This makes the tests shorter and hence easier to read, avoids
re.compile calls and manual failure message composing.
In some cases assert_multi_regex could be used to avoid the explicit loops.

While doing that I put the re.compile into the assertion instead of assigning to a variable and remove the call when there are no flags required as assertRegex accepts strings or compiled expressions

Examples:

-        regex = re.compile(os.path.join(tmpdir, r'easybuild-foo-1\.2\.3-[0-9]{8}\.[0-9]{6}\.log$'))
-        self.assertTrue(regex.match(res), "Pattern '%s' matches '%s'" % (regex.pattern, res))
+        self.assertRegex(res, os.path.join(tmpdir, r'easybuild-foo-1\.2\.3-[0-9]{8}\.[0-9]{6}\.log$'))

-        regex = re.compile(r"^eb toy-0.0.eb --robot --debug -l", re.M)
-        self.assertTrue(regex.search(txt), "Pattern '%s' should be found in: %s" % (regex.pattern, txt))
+        self.assertRegex(txt, re.compile(r"^eb toy-0.0.eb --robot --debug -l", re.M))

-            fail_msg = "Pattern '%s' should be found in: %s" % (guarded_load_regex.pattern, modtxt)
-            self.assertTrue(guarded_load_regex.search(modtxt), fail_msg)
-            fail_msg = "Pattern '%s' should not be found in: %s" % (recursive_unload_regex.pattern, modtxt)
-            self.assertFalse(recursive_unload_regex.search(modtxt), fail_msg)
+            self.assertRegex(modtxt, guarded_load_regex)
+            self.assertNotRegex(modtxt, recursive_unload_regex)

Continuation of #4205 , #4170, #5134 to remove usage of assertTrue & assertFalse as for almost everything there is a better alternative

Also regex assertions are over-used. In some places assertIn or even assertEqual could be used which is clearer and faster.
However the replacements done here were mostly regex-based with lot's of manual inspection to find good patterns, and finding those where assertIn would work is even more difficult.

[boegel]

@Flamefire merge conflicts to resolve here...

[Flamefire]

Rebased

[boegel]

merge conflicts again...

As with #5223, I think it would help to break this into smaller PRs, which are easier to review/merge, and less likely to get blocked by merge conflicts

[Flamefire]

This is a search&replace (using regex) which I think is better to do once, especially as it is only test code so mistakes would a) turn up in CI and b) are not critical to users. So I would not recommend multiple PRs but just do some quick spot checking.

If you still want separate PRs: How small do you want them? More PRs is more work but quicker to review.

[boegel]

This is a search&replace (using regex) which I think is better to do once, especially as it is only test code so mistakes would a) turn up in CI and b) are not critical to users. So I would not recommend multiple PRs but just do some quick spot checking.

If you still want separate PRs: How small do you want them? More PRs is more work but quicker to review.

Point taken. It's just trouble to get this reviewed, since it keeps "bitrotting" in between times we manage to take another look at it, and leading to merge conflicts (as is again the case now).

Naively I would say one PR per test module, but that's perhaps a step too far (that would be 25 tiny PRs).
How about PRs that change no more than say 100-ish lines, and only touch a handful of test modules (5-ish)?

[Flamefire]

How about PRs that change no more than say 100-ish lines, and only touch a handful of test modules (5-ish)?

Ok done, all PRs mentioned in the description of this one. I'd keep this open in case at some point someone likes to merge the remaining changes in one go

[Flamefire]

All merged, no new occurrences in develop. Thanks!